若(sinθ+cosθ)/(sinθ-cosθ)=2,则sin(θ-5π)*sin(3π/2-θ)等于?

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若(sinθ+cosθ)/(sinθ-cosθ)=2,则sin(θ-5π)*sin(3π/2-θ)等于?

sin(θ-5π)=-sinθ,sin(3π/2-θ)=-cosθ
(sinθ+cosθ)/(sinθ-cosθ)=2→sinθ=3cosθ
sinθ^2+cosθ^2=1
cosθ^2=0.1,sinθ^2=0.9
sin(θ-5π)*sin(3π/2-θ)=-sinθ*-cosθ=3cosθ^2=0.3